One method of delivering medication is by a metered dose aerosol inhaler device and such devices may be made to provide oral or nasal delivery. Early inhalers are described in U.S. Pat. Nos. 3,361,306; 3,183,907; 3,565,070; 4,206,758; 4,803,978; 4,934,358; 4,955,371; 5,060,643; 5,351,683; 5,062,423.
An example of a typical metered dose inhaler is described herein. A pressurized dispensing canister is filled under pressure with a drug dissolved in a liquefied propellant, or micronized particles suspended in a liquefied propellant. Surfactants may be dissolved in the aerosol formulation as well. The canister is fitted with a metering valve that is movable from an inactive to an active (depressed dispensing) position. The canister containing medication is placed in the upper arm of an elbow shaped housing with the metered dose dispensing valve in position to deliver medicament through the lower arm portion and into a patient's mouth or nose, when the canister and thereby the dispensing valve is depressed against the housing. The lower arm of the housing may be configured to aid in delivery of the medication orally or nasally.
Metered dose inhalers are an accepted means for delivering medications, such as, bronchodilators, corticosteroids, and anti-allergics, in small doses to the respiratory tract. Metered dose inhalers may be a route for delivery of many other medications.
However, if nasal delivery is the desirable mode and only an oral inhaler is available, a satisfactory result may not be achieved. After the discontinuance of the use of chlorofluorocarbons (CFC's), the new non-CFC aerosol inhalers were not necessarily available with nasal delivery adaptation.
Although the same medicine may be prescribed for oral and nasal delivery, for example, beclomethasone dipropionate, the mode of delivery may need to be different to achieve the best treatment. In the past aerosol inhalers were sold to deliver this drug to the nasal mucosa for treatment of allergic rhinitis. Oral configurations of metered-dose aerosols are usually of a shape and size that is not conducive to insertion into the nostril of a human or animal.
In addition, there are side effects from oral delivery of corticosteroids that could be avoided through nasal delivery. The treatment of asthma and other lung conditions with oral inhalation steroids is associated with fungal growth in the oral cavity. This is likely due to the deposition of corticosteroids in the oral cavity. Patient instructions on the use of oral inhalation aerosols recommend that the patient rinse their mouth to remove oral corticosteroids in an attempt to reduce the incidence of candidiasis. The delivery of corticosteroids for inhalation through the nose bypasses the oral cavity and thus reduces the incidence of oral candidiasis.
The simultaneous treatment of rhinitis and asthma by delivery of a steroid through the nose rather than delivering the steroid to the lungs via the mouth and the nose locally was described in W. Pedersen, I. Hjuler, H. Bisgaard, N. Mygind, Allergy, April 1998, 53(4):383-7. Pedersen et al. found that nasal inhalation of a corticosteroid from a spacer offers a simple and effective treatment for both rhinitis and asthma. Since particles from the air, such as allergens, are deposited primarily in the nasal cavities, allergic inflammation would occur in the entire airway mucosa. Pedersen et al. used a spacer to deliver medication to the nasal mucosa. In their experiment a pressurized aerosol was attached to a spacer device and the steroid was inhaled through the nose from the spacer device. The use of a spacer, they believed, provided a more uniform intranasal drug distribution, since only inhaled air delivered the drug.
There are a number of patents that deal with the difficulty in timing the inhalation of breath with the depression of the dispensing valve—U.S. Pat. Nos. 6,615,826; 4,972,830; 5,758,638. There are other patents that deal with the adaptation of an inhaler for nasal delivery with a mask, particularly for animals, for instance, U.S. Pat. Nos. 6,510,818 and 5,666,948. However, a drawback of a spacer or mask is the decreased dose of medication due to the increased distance to the nasal cavity, and increased surface on which the medication may adhere. To avoid this problem by increasing the amount of medication dispensed is uneconomical.
Aqueous nasal sprays delivered by pump action are an alternative to aerosol inhalers. However, with aqueous delivery, a set concentration is delivered to the mucosa since subsequent sprays result in the extra aqueous solution being swallowed. In contrast, a metered dose aerosol delivery allows a greater concentration of inhalant to be delivered to the nasal mucosa. Since the propellant is a vapour that dissipates, subsequent doses result in extra medication being deposited on the nasal mucosa.
Therefore it would be desirable to provide a method of adapting an oral metered dose aerosol inhaler and also to provide an adaptor for an oral metered dose aerosol inhaler to enable effective nasal delivery.